Please expand on what was inadequate about fsolve.
- Did it not converge at all?
- Did it not converge to the solution you want to see? (After all, such a problem will have multiple solutions in general.)
- Did it not converge quickly enough for your needs?
- Was the solution obtained from fsolve not accurate enough for you?
- Do you need a symbolic solution?
The point is, some of these issues can be viewed as merely one of inadequate starting values. Or, you may want a global solver. There is a global optimization toolbox.) Or you may be looking for ALL possible solutions.
And of course, it is likely that no symbolic solution exists, since the problem will be equivalent to solving for the roots of a high order polynomial.
So for a better answer, we need some help here.